Amide-imide-ester wire enamels

ABSTRACT

Polymeric amide-imide-ester wire enameling compositions are prepared from (1) a monoanhydride of an aromatic tricarboxylic acid, e.g. trimellitic anhydride, (2) an aromatic primary diamine compound and (3) either polyfunctional acids and polyhydroxy compounds or the polyesters thereof. At least a portion of the polyol or polyhydroxy compound is a tris (hydroxyalkyl) isocyanurate, e.g. tris (hydroxyethyl) isocyanurate. The polyfunctional acids (3) comprise an acid component selected from the group consisting of trimellitic anhydride, isophthalic acid and esters of isophthalic and terephthalic acid. The polymeric amide-imide-ester may be blended with terephthalate or isophthalate polyesters, polyisocyanates and other materials. One particularly suitable polyisocyanate is prepared from dimethylterephthalate, tris (2-hydroxyethyl) isocyanurate and tolylene diisocyanate. Small amounts of aliphatic amino compounds, aliphatic polyols and other flexibilizing materials may be incorporated into either the polymeric amide-imide-ester or the polyester blended therewith. A variety of block and modified block polymers may be made. Imidization occurs during the preparation of the polymeric amide-imide-ester so that the condensed water is removed before the fluid compositions are applied and cured.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of application Ser. No. 292,244 filedSept. 25, 1972 and now abandoned which was a continuation of applicationSer. No. 61,105 filed Aug. 5, 1970, now also abandoned which was acontinuation of application Ser. No. 555,211 filed Mar. 4, 1975 nowabandoned. Ser. No. 61,105 was a division of Ser. No. 730,833 filed May22, 1968 which issued as U.S. Pat. No. 3,555,113.

BACKGROUND OF THE INVENTION

This invention relates to soluble amide-imide-ester polymericcompositions and resinous blends containing such compositions, tomethods of preparing such compositions and to the solid resinouscoatings that such compositions provide, particularly on metalelectrical conductors such as copper wire.

Terephthalate and isophthalate polyester compositions have been widelyaccepted in insulating electrical conductors such as copper and aluminumwire and foil. The heat shock and solvent shock properties of thesepolyesters, including those employing tris(2-hydroxyethyl)isocyanurateas a polyol component, have been considered one of their mainweaknesses. Some manufacturers employ linear polyester overcoats inefforts to upgrade the heat and solvent shock. While some of thesepolyester compositions have acceptable thermal properties for most uses,applications which require higher, more reliable thermal life areincreasing.

Aromatic polyimide compositions, primarily those derived from aromaticdianhydrides and primary aromatic diamines are employed as coatingswhere continuous reliable operation at temperatures in the 200°-220° C.range is required. These compositions are derived from aromatic polyamicacid precursors that are prepared in and are soluble in expensivesolvent systems. The imidization occurs after these precursors have beenapplied to the conductor and the condensation (splitting out a mole ofwater per mole of imide groups formed) has a tendency to produceblistered coatings.

Polyester-imide compositions have been made in an effort to strike abalance between the properties of the foregoing polyesters andpolyimides. In general, the compositions that have substantial imidecontent must employ expensive solvents and are characterized by asubstantial number of disadvantages of the polyimides. The compositionsthat are soluble in inexpensive solvent systems have a low imide contentand are thus very close to the polyester compositions in properties.

SUMMARY OF THE INVENTION

None of the foregoing general compositions, indeed none known in theprior art, approaches what might be fairly classed as a universalcoating for magnet wire, i.e. a coating which combines the requiredchemical, physical and thermal properties for most major uses with lowcost. A coating must have good flexibility, adhesion to the conductor,scrape hardness, abrasion resistance, high temperature heat shockresistance, resistance to hot solvents, resistance to refrigerants, highdielectric strength and good thermal and oxidative stability. In theliquid state, the composition must also coat the conductors smoothly andrapidly and be converted to a solidified coating at a wide range ofspeeds in conventional wire enameling towers. An essential key touniversality is, of course, cost.

Accordingly, it is an object of this invention to provide a coatingcomposition for electrical conductors that will possess the requiredmechanical, physical and chemical properties, as an insulating coatingon the conductors, for most major uses and which may be made at arelatively low cost.

It is another object of this invention to provide a wire enamelingcomposition that will provide blister-free coatings having an improvedheat and solvent shock, resistance to refrigerants and resistance to theabrasion of automatic winding machines and that may be employed with lowcost solvent systems.

Another object of the invention is to provide a method for making anaromatic amide-imide-ester polymer having a high molecular weight and asubstantial imide content in a low cost solvent system.

Yet another object is to provide a novel isocyanate which may be blendedwith the novel polymeric amide-imide-esters of this invention and/orwith similar compositions.

Other objects of the invention will, in part, be obvious and will, inpart, appear hereinafter.

BRIEF DESCRIPTION OF THE DRAWING

For a more complete understanding of the present invention, reference ismade to the following description taken in conjunction with theaccompanying drawing wherein:

FIG. 1 is a fragmentary isometric view of conductor provided with aninsulating enamel coating of this invention;

FIG. 2 is a cross-sectional view of a conductor insulated with a fibrousmaterial and an enamel of this invention; and

FIG. 3 is a cross-sectional view of a conductor provided with aninsulated conductor of this invention having an under and an overcoatwherein one of the coatings is a composition of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

It has now been discovered that certain aromatic amide-imide-esterpolymeric compositions, particularly suitable for coating electricalconductors, may be prepared from reactants comprising (1) amonoanhydride of an aromatic tricarboxylic acid, (2) an aromatic primarydiamino compound and (3) a polycarboxylic acid component and apolyhydroxy component or the polymeric ester therefrom, wherein at leasta portion of the polyol is a tris (hydroxyalkyl) isocyanurate orcyanurate. The polymeric amide-imide-ester itself will provide desirableinsulating coatings but it may be blended with other compositions,particularly certain polyesters, to provide additional advantages. Thesecoating compositions may be most conveniently described in terms ofreactants and proportions and the specific sequence of reactions.

Suitable coating compositions, in accordance with this invention, arederived from (A) 40 to 55 equivalent percent of an acidic componentcomprising (1) at least 13 equivalent percent of a monoanhydride of anaromatic tricarboxylic acid, (2) up to 31 equivalent percent of at leastone acidic compound selected from the group consisting of isophthalicacid and the lower dialkyl esters of isophthalic and terephthalic acid,(3) up to 10 equivalent percent of at least one acidic compound selectedfrom the group consisting of aliphatic dicarboxylic acids containingfrom 4 to 10 carbon atoms and esters and anhydrides thereof, (4) up to10 equivalent percent of a tetra alkyl titanate wherein the alkyl groupscontain 1 to 4 carbon atoms and (5) up to 10 equivalent percent of apolyisocyanate, particularly the novel polyisocyanate compounds(Ester-Urethane-Isocyanate) described hereinbelow and the blocked trimerof tolylene diisocyanate and (B) 45 to 60 equivalent percent of anamino-polyol component comprising (1) at least 8 equivalent percent ofan aromatic primary diamino compound, (2) up to 5 equivalent percent ofan amino compound selected from the group consisting of aliphaticprimary diamines, melamine and piperazine, (3) at least 15 equivalentpercent of a polyol having at least three hydroxyl groups, preferably atris(hydroxylalkyl)isocyanurate and (4) up to 25 equivalent percent ofan aliphatic diol.

The term "equivalent percent" as employed herein is calculated accordingto the following formula: ##EQU1## All ingredients which have reactivegroups are considered in the sum (Σ) which serves as the divisor in theformula, whether already reacted in the soluble coating composition oravailable for reaction when cured on the electrical conductor. Thefunctional groups are the anhydride, carboxyl, hydroxyl, amino,titanate, ester and isocyanate groups. The dicarboxylic acidiccompounds, dihydric alcohols and diamines are bifunctional. Thefunctionality of other polyols, for exampletris(2-hydroxyethyl)isocyanurate, will have a functionality equal to thenumber of hydroxyl groups present. Trimellitic anhydride should beconsidered to be trifunctional in the polyester reaction (with thepolyols) but bifunctional in the amide-imide reaction (with the amine).

The anhydride group is monofunctional in imide formation. In thecalculations, the functionality of the trimellitic anhydride in thereaction with the diamine should be calculated on the basis that all ofthe possible imidization occurs first (with the anhydride group) andthat the remaining carboxyl groups of the trimellitic anhydride arereactive with amino groups to form amide linkages and then hydroxylgroups to form ester linkages. It is essential, in accordance with thisinvention, for the molar ratio of the trimellitic anhydride to aromaticprimary diamine to be in the range from about 0.8:1 to 1.8:1 in theamide-imide reaction of the polymer formation. Above the 1.8:1 ratio,the solubility of the polymer in the low cost solvent systems (e.g.cresylic acid) becomes marginal. With a 2:1 ratio, there would beessentially no amide linkages in the polymer to contribute to solubilityin the low cost solvent system. The amount of imide in polymerscontaining no amide solubilizing groups would be limited. Compared toester linkages, the amide linkages provide a higher degree of heatshock. In the ranges below about 0.8:1 there would be fewer imidelinkages in the polymer, contributing to a lower solvent resistance andthermal resistance.

The tetraisopropyl titanate, employed as a reaction promoter in many ofthe examples, is considered to be tetrafunctional. Where catalysts areemployed, they are not considered in the calculations of equivalents. Inthe calculation of equivalents, the blocked trimer of tolylenediisocyanate (Mondur SH) is considered to be trifunctional with amolecular weight of 1050. The novel ester-urethane-isocyanate(hereinafter described) adds to the total functionality of the dimethylterephthalate, THEIC and tolylenediisocyanate since all these reactiveor reacted groups are contained in the prepolymer which is blended inwith this novel isocyanate.

Essential to the ester formation in these compositions is at least 15equivalent percent of a polyol having three or more hydroxyl groups,such as tris(hydroxyalkyl)isocyanurate. The most suitable and preferredexample is tris(2-hydroxyethyl isocyanurate). The tris(2-hydroxyethyl)isocyanurate, hereinafter called THEIC for convenience, is readilycommercially available. It should also be understood that the tautomericanalogs of the isocyanurate compounds, e.g.tris(2-hydroxyethyl)cyanurate, may be employed. These latter cyanuratetriesters may be in the enol(cyanurate) form at room temperature butchange to the keto(isocyanurate) form at esterifying temperatures. Otherpolyols having three or more hydroxyl groups, such as glycerol,trimethylolethane, trimethylolpropane, penetaerythritol and mixturesthereof may be substituted for the preferred THEIC in whole butpreferably only in part. It should be understood that a significantvariation in thermal properties may occur as the amount of THEIC isreduced and, as will be apparent from the examples hereinbelow, that itis preferred to use THEIC alone as the polyol having 3 or more hydroxylgroups.

Part of the foregoing trihydric polyol may be advantageously replaced byan aliphatic diol or glycol such as ethylene glycol, 1,4-butanediol,1,5-pentanediol, hexamethylene glycol, 1,4-cyclohexanedimethanol,neopentyl glycol and mixtures thereof. As little as one equivalentpercent is considered to be an effective amount for providing someimprovement in flexibility. Up to 25 equivalent percent may be employedwith no undue sacrifice in thermal properties.

Also essential to the formation of the compositions of this invention isat least one compound selected from the group consisting of isophthalicacid and the lower dialkyl esters of isophthalic and terephthalic acidand a monoanhydride of an aromatic tricarboxylic acid. As will becomeapparent from the examples, the overall stoichiometry of the reactantsis the same whether the coating compositions are homopolymers,copolymers or block copolymers or blends thereof. Suitable coatingcompositions of any of the various types may be made so long as thestoichiometry of all reactants in the amide-imide-ester formation ismaintained. Thus, from 40 to 55 equivalent percent of acid and from 45to 60 equivalent percent of polyol are employed in the ester formationwhere only the ester forming ingredients are prereacted to form a highmolecular weight polyester which is then reacted with the TMA anddiamine. All of the ingredients are considered for calculatingequivalent percentages irrespective of when they are added. Unreactedfunctional groups of the polyester will later react with the functionalgroups of the amide-imide forming ingredients. The excess carboxylgroups of the polyester would react with amino groups to form an amidelinkage whereas an excess of hydroxyl groups in the polyester wouldreact with the carboxyl groups of the anhydride to form additional esterlinkages. A polyester with excess hydroxyl groups is preferred. Thisreaction between the excess groups of the polyester (or ingredientstherefor) and the polyamide-imide components or ingredients improves thesolubility of the imide containing polymer and form copolymers (block,modified block, etc.) either before or after the coating compositionsare applied to the conductor or both before and after the application.

At least 10 equivalent percent of the monoanhydride of an aromatictricarboxylic acid, for example trimellitic anhydride, is essential inthe amide-imide part of the polymer formation for a satisfactory minimumamide-imide formation. Small amounts of tetracarboxylic aromaticdianhydride may be included to form imide groups but the amounts must belimited to prevent formation of insoluble imide from thesetetracarboxylic derivatives. Solubility in the hereinafter describedsolvent systems is mandatory if the advantages of low cost are to bemaintained. About 5 equivalent percent of the tetracarboxylic aromaticdianhydride is a maximum limit. Examples of such dianhydrides arepyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, etc.

At least 8 equivalent percent of an aromatic primary diamono compoundmust be included. The aromatic diamino compounds may contain one or morearomatic rings. Where two rings are present, the rings may be bridged byvarious divalent radicals such as oxy, carboxy, sulfo, sulfonyl, amidoor alkylene radicals. The rings may, of course, be joined together withno bridging groups or they may be fused rings. The essential requirementis the presence of at least two reactive primary amino groups. Methylenedianiline and m-phenyline diamine are preferred but other amines such as4,4'-diaminodiphenyl ether, 3,4'-diaminobenzanilide and many others maybe employed. Melamine, piperazine and aliphatic amines may be employedin small amounts ranging from 0.5 to 5 equivalent percent.

From 0.5 to 10 equivalent percent of an aliphatic dicarboxylic acidcomponent may be included to afford improvements in flexibility or otherproperties. Dicarboxylic acids, and esters or anhydrides thereof,containing from 4 to 10 carbon atoms are suitable. Examples are sebacicacid, adipic acid, azelaic acid and maleic anhydride.

Titanate esters, e.g. tetra alkyl titanates and tetra cresyl titanate,may be included in the polyester reactant mixture to both catalyze theesterification reaction and improve the adhesion of the cured coating tothe metal conductor. From 0.5 to 8 equivalent percent of the titanateester may be included. The alkyl groups of the tetra alkyl titanatecontain 1 to 4 carbons. Non-reactive esterification catalysts may,however, be employed instead. Such catalysts are known in the art. Theyare generally octoates, linoleates, naphthenates, etc. of metals such aszinc, cobalt, lead, etc. The titanate ester may, of course, be blendedwith compositions made with non-reactive catalysts.

As will become apparent from the specific examples, the best combinationof properties is provided where the ester-forming ingredients are firstadvanced to a thread-forming stage and the amide-imide ingredients arethereupon added to form a polymer containing the imide and amidelinkages. Additional polyester may be cold blended with the polymericamide-imide-ester or additional polyester ingredients may be added forfurther reaction with the polymeric amide-imide-ester. Polyester amidesand/or polymeric amide-imide-esters may also be a part of the blend. Thecold blends of the polymeric amide-imide-ester and terephthalatepolyesters form block copolymers that give the best thermal life. Inaddition to the thermal life properties, the block copolymers of thecold blends provide a combination of properties not attainable by mixingall of the ingredients together in a single reaction vessel,particularly the properties of heat shock, cut-through, flexibility andbaking range, although these latter compositions have better propertiesthan the prior art polyesters.

The relative proportions of the components of the cold polymeric blendsmay also be conveniently described in terms of total solids weight. Asolution of a polymeric amide-imide-ester composition may be coldblended with 20 to 60 percent by weight on a total solids basis of aterephthalate polyester, particularly a terephthalate-THEIC-ethyleneglycol polyester. A minor proportion (10 to 20 percent by weight on atotal solids basis) of a blocked polyisocyanate, for example the phenolblocked trimer of tolylene diisocyanate, may be included. From 1 to 6percent by weight of titanate ester, based on the total solids, may beadded to the blend.

Either the polymeric amide-imide-ester or the polyester or the polyesteramide component of the blend may contain a flexibilizing modifier. Thepreferred polyester component described above includes ethylene glycolas a modifier but other diols such as neopentyl glycol, 1,4-butanediol,hexamethylene glycol, 1,5-pentanediol and 1,4-cyclohexanedimethanol areother examples. Aliphatic dicarboxylic acids such as sebacic, azelaic,etc. may also be included.

The coating compositions may also be blended with from about 1 to 10percent, on a total solids weight basis, of a phenolic resin. A suitablephenolic resin may be derived from 50 to 65 equivalent percent of aphenol (such as phenol, m,p,-cresol, cresylic acid, or mixtures thereof,and 35 to 50 equivalent percent of an aldehyde (such as formaldehyde)catalyzed by a tertiary amine (such as triethanolamine).

The compositions of this invention are soluble in solvents such ascresol, cresylic acid and phenol. The compositions may be furtherdiluted to a suitable coating viscosity with cresylic acid and/or withan aromatic hydrocarbon diluent having a preferred boiling range ofabout 135° to 300° C. The aromatic hydrocarbon diluent may constitutefrom 30 to 50 weight percent of the total solvent system. Thecompositions may be dip-coated, die-coated, etc. on wire, foil and thelike using standard procedures.

For convenience of identifying the various ingredients employed in theexamples and in the various summaries that will follow, abbreviationswill be employed in accordance with the following Table I.

                  TABLE I                                                         ______________________________________                                        Abbreviation                                                                            Ingredient                                                          ______________________________________                                        EG        ethylene glycol                                                     THEIC     tris (2-hydroxyethyl) isocyanurate                                  MPD       m-phenylenediamine                                                  MDA       methylene dianiline                                                 TMA       trimellitic anhydride                                               DMT       dimethylterephthalate                                               IPT       tetraisopropyl titanate                                             TDI       tolylene diisocyanate (80% 2,4 and 20% 2,6)                         SA        sebacic acid                                                        PTD       1,5 pentanediol                                                     NPG       neopentyl glycol                                                    CHDM      1,4 cyclohexanedimethanol                                           HMG       hexamethylene glycol                                                BTD       butanediol 1,4                                                      AA        adipic acid                                                         AZA       azelaic acid                                                        ED        ethylenediamine                                                     ______________________________________                                    

As will be apparent from the following description, various tests areconducted on enameled or resin insulated wire to evaluate thesuitability of a resinous coating composition as wire insulation. Theproperties described in the following examples and tables weredetermined in accordance with the following procedures:

Baking Range: This is a measure of the range of wire speed (in feet perminute through a 15 foot enameling tower at a hot spot temperature of430° C.) that will provide a smooth coating which passes both a 1XMandrel Test (no crazing, cracks or other flaws in the coating visibleto the eye when the wire is wrapped about its own diameter) and a QuickSnap Test.

Quick Snap Test: This is primarily a measure of flexibility of theenamel film but also indicates degree of adhesion. It is employed as acontrol test to determine if enamel film is underbaked or overbaked. Awire 12 inches in length between a stationary and a movable chuck iselongated rapidly so that the wire breaks at any distance more than oneinch from either fastener. The enamel film should be free of any flawsor imperfections to pass these test.

Flexibility: This is a measure of the ductility of an enamel film on aconductor and indicates the degree to which a wire can be elongated andremain free of cracks, faults, and other imperfections. The testsimulates the stretching of a wire when passing over small radiipulleys, through guides, and on coil forms as it is being wound intofinished coils. The test is conducted by mounting one end of a length ofenameled wire in a stationary and the other end in a movable chuck whichare 10 inches apart. Each one of a series of wires is elongated to afixed percentage until flaws appear in the enamel film as the wirebreaks. The maximum elongation, in percent, that the enamel film willremain flawless and free of flaws or imperfections after also beingwrapped about a IX mandrel is the reported figure.

Abrasion Resistance: This is a measure of the enamel film hardness, andthe degree of adhesion of the film to the base metal and/or the cohesionbetween enamel layers. This test provides an indication of the abilityof the enamel film to withstand winding abuses. The test is also used inthe coating operation to determine the proper bake the enamel must begiven to obtain the best possible properties. There are generally fourtest procedures which are used and they are described as follows:

(a) Unilateral Scrape--A constant load on a 9 mil diameter piano wire,which is at right angles to the wire, moves along the length of the wirewith an increasing lever arm until the insulation is removed and theneedle makes contact with the conductor. The distance the weighted headtravels multiplied by the weight gives a numerical value for scraperesistance of the insulation.

(b) General Electric Repeated Scrape Abrasion--Abrasion of the wire filmis accomplished with a cylindrical surface of a 16 mil diameter #140needle which is moved back and forth a distance of 3/8 inch at rightangle to the wire under a load of 700 grams. The number of cyclesrequired to cause the needle to break through the enamel film is theGESA value.

(c) Westinghouse Scrape--A 12 inch length of enameled wire is pulledunder a 9 mil diameter weighted steel piano wire at right angles to thepiano wire for a distance of 4 inches on each of 4 sides 90° apart. Theweight required to scrape off one-half the enamel of any one side to theconductor is considered the scrape value.

(d) Emerson Scrape--The wire is drawn at 60 ft./min. under and at rightangle to a weighted 51 mil diameter needle which is placed on the movingwire and removed by a cam action assembly. The weight required to scrapethrough to the conductor 8 out of 10 times is the reported single scrapevalue.

Unless otherwise specifically noted, Abrasion Resistance was determinedby method (b).

Heat Shock: This is a measure of the ability of the enamel film towithstand heat while in a stressed condition, a condition encountered,for example, in heated wound magnet wire coils. A length of enameledwire is wrapped around its own diameter twenty times. Each one of aseries of test samples is placed in an oven at various increasingtemperatures. The highest temperature which the stressed coils withstandafter being heated for one hour and cooled to room temperature, withoutvisual breaks or failures occurring in the enamel film is considered theheat shock value. Visual observation is made under a microscope atapproximately 23× magnification. Temperatures are increased in 25° C.increments.

Cut-Through Temperature: This is a measure of the ability of an enamelfilm to resist flow under heat and pressure as encountered, for example,in heated random wound motor armature coils. This is sometimes called athermoplastic flow test.

Two enameled wires are placed horizontally and at right angles to eachother in a suitabe jig with a 1000 gram weight centered on the wires atthe cross-over point. The temperature of the assembly raised at aconstant rate of 5 degrees per minute until the two conductors came incontact with each other which is detected by means of electricalcircuitry. The temperature at which this short circuiting occurs isconsidered the cut-through temperature value.

Thermal Stability: This is a test measuring the expected thermal classrating of varnished or unvarnished magnet wires in electrical equipmentand is based on the theory of electrical insulation deteriorationtreated as a chemical rate phenomenon. The test procedure is thatprescribed in IEEE No. 57. Data is reported as hours to failure at agiven temperature.

Weight Loss: This is a measure of the loss in weight of an enamel filmon aging at elevated temperatures. This weight loss is caused normallyby loss in uncombined solvents, further polymerization and splitting offof byproducts associated with the enamel, and thermal degradation of thepolymeric structure.

The test includes weighing one-quarter gram samples of the wet enamel ina 2 inch diameter aluminum dish, and then heating the enamel toeliminate the solvents and thinners and complete the polymerizationreaction. The resulting enamel film is initially heated at 200° C. for24 hours and then aged at selected temperatures, normally 200° C., 225°C. and 250° C. Samples are reweighed periodically and the cumulativeweight loss calculated on the weight of the sample after the initial 24hour curing step.

Other tests that may have been conducted are specifically described whendata therefrom is reported hereinbelow.

For a convenient consideration of the properties of the coatings in thefollowing examples, the test data obtained is summarized here in TablesII and III.

                                      TABLE II                                    __________________________________________________________________________    Properties of Wire Enamels on #18 A.W.G. Wire (0.040") - Heavy Build                 Baking.sup.1                                                                              Abrasion.sup.3                                                                      Heat.sup.4                                                                          Cut.sup.5                                                                            Thermal Life, Hrs., at Temp.                                                  °C..sup.6                        Example No.                                                                          Range                                                                              Flexibility.sup.2                                                                    Resistance                                                                          Shock, °C.                                                                   Through, °C.                                                                  Varnish 275 250                                                                              225  200                 __________________________________________________________________________    1      17-22                                                                              20-25   50-100                                                                             175   386-401                                                                              None     88  372                                                                              904    9500                                                   Silicone                                                                              156 1094                                                                             5300 --                  2      19-26                                                                              30-35  30-40 125   375-395                                                                              None     77  350                                                                              610   >5000             3      17-25                                                                              10-20  45-70 225   360-367                                                                              None    260 1116                                                                             1388 --                                                        Silicone                                                                              372 1272                                                                             2770 --                  4      17-25                                                                              10-30  15-70 250   285-340                                                                              None    217  732                                                                             1595 --                  5      19-28                                                                              10-20  20-80 200-225                                                                             390-400                                                                              None    320 1284                                                                             3190 --                                                        Silicone                                                                              336 1764                                                                             4000 --                  6      17-25                                                                              10-25   40-100                                                                             225   390-410                                                                              None    232 1282                                                                             8000 >19,700             7      17-22                                                                              10-15   80-150                                                                             225   350-360                                                                              None    219 1644                                                                             4200 --                  8      17-22                                                                              10-20  60-70 225-250                                                                             400-407                                                                              None    324 1812                                                                             6040 --                  9      17-25                                                                              10-20   55-185                                                                             225   385-400                                                                              None    278 1020                                                                             2700 --                  10     17-25                                                                              15-30   20-100                                                                             200   330-390                                                                              None     28  168                                                                             1800 >30,000                                                   Silicone                                                                               28  252                                                                             8180  33,100             11     17-28                                                                              20-35  20-60 175-200                                                                             280-390                                                                              None     64  252                                                                             3450 >27,400                                                   Silicone                                                                               84 3852                                                                             11,600                                                                             >26,200             12     17-25                                                                              15-35   20-100                                                                             225   340-360                                                                              None     78  372                                                                             4116   >9000                                                   Silicone                                                                               36 1740                                                                             8060 >33,100             13     15-22                                                                               5-20   40-100                                                                             250   330-340                                                                              None     24  168                                                                             5050 >30,000                                                   Silicone                                                                               36  984                                                                             6640 >33,100             14     17-28                                                                              20-30  25-60 225   340-360                                                                              None     78 1680                                                                             6972 --                  15     19-32                                                                              20-35  26-50 225   320-350                                                                              None     36  948                                                                             4450 --                  16     17-22                                                                              20-25   80-100                                                                             225   390-395                                                                              None     70 2292                                                                             8316 --                  17     19-28                                                                              10-15  40-90 200   390-410                                                                              None    212 1620                                                                             7300 --                                                        Silicone                                                                              276 2472                                                                             8652 --                  18     17-25                                                                              10-30   40-100                                                                             225   390-420                                                                              None    156 1920                                                                             5380 --                                                        Silicone                                                                              108 2328                                                                             7150 --                  19     17-32                                                                              10-30  30-80 225   300-350                                                                              None    256 1824                                                                             2000 --                  20     17-32                                                                              20-35  25-40 200   370-390                                                                              None    102 1128                                                                             6580 >20,300                                                   Silicone                                                                               74 1340                                                                             5960 >17,800             21     17-28                                                                              15-35  20-90 175-200                                                                             370-410                                                                              None     80  624                                                                             8484 >10,000             22     17-25                                                                              10-25  50-90 200   380-400                                                                              None    121  516                                                                             10,700                                                                             --                                                        Silicone                                                                              228 2532                                                                             11,600                                                                             --                  23     17-28                                                                              15-25   25-130                                                                             200   375-405                                                                              None    116 1968                                                                             7500 >21,000                                                   Silicone                                                                              177 2592                                                                             8316 >21,000             24     17-28                                                                              10-20   40-150                                                                             200   370-410                                                                              None    165  768                                                                             7220 >22,000                                                   Silicone                                                                              560 2616                                                                             9912 >11,000             25     17-28                                                                              15-25   30-100                                                                             225   375-400                                                                              None    310 1320                                                                             4950 >17,800                                                   Silicone                                                                              392 2160                                                                             7400 >20,700             26     19-25                                                                              10-20   40-150                                                                             225   400-420                                                                              None    204 1982                                                                             4620 --                                                        Silicone                                                                              512 1968                                                                             4664 --                  27     17-36                                                                              25-35   40-190                                                                             225-250                                                                             350-370                                                                              None    164  876                                                                             7900 >16,600                                                   Silicone                                                                               65 1512                                                                             7230 >15,900             28     17-36                                                                              30-35  15-30 225-250                                                                             345-380                                                                              None     44  636                                                                             1092 >13,800             29     17-36                                                                              30-35   30-100                                                                             225- 250                                                                            305-330                                                                              None     20  120                                                                              420   >4116             30     17-32                                                                              30-35  20-50 225-250                                                                             320-360                                                                              None     44  636                                                                             4200 >13,800             31     17-32                                                                              15-30  20-60 225-250                                                                             305-370                                                                              No Data                                 32     17-32                                                                              25-35  28-76 225-250                                                                             340-355                                                                              No Data                                 33     17-36                                                                              15-30  20-90 225-250                                                                             300-360                                                                              No Data                                 34     17-36                                                                              25-30  30-80 225-250                                                                             330-365                                                                              No Data                                 35     17-36                                                                              20-35  17-40 225-250                                                                             300-350                                                                              No Data                                 36     19-32                                                                              20-25  20-30 225-250                                                                             380-400                                                                              No Data                                 37     17-32                                                                              10-35  26-94 250   370-400                                                                              None    110 1308                                                                             >5500                                                                                >5500                                                   Silicone                                                                               84 1170                                                                             >5500                                                                                >5500             38     17-36                                                                              10-35  30-40 225-275      No Data                                 39     19-36                                                                              10-35  20-45 225-275      No Data                                 40     17-40                                                                               5-35  26-72 225-275                                                                             380    No Data                                 41     19-36                                                                              10-35  26-64 225-275                                                                             385    No Data                                 42     17-36                                                                               5-35  32-80 225-275                                                                             390    No Data                                 43     19-25                                                                              10-20  20-40 225   390-405                                                                              None    1152                                                                              5192                                                                             12,600                                                                             --                  44     --   --     --    --    --     Imide Overcoat                                                                        296 2680                                                                             17,500                                                                             --                  45     17-32                                                                              10-35  70-95 >300  --             140 1332                                                                             >2500                    __________________________________________________________________________     .sup.1 Baking range is speed range (in feet per min. through a 15foot         tower at a hotspot temperature of 430° C.), coating smoothly,          passing IX mandrel and passing quick snap test.                               .sup.2 Flexibility is range of maximum % elongations which pass IX mandre     over entire baking range.                                                     .sup.3 Abrasion Resistance is number of strokes to failure, 16 mil            diameter knife edge, 700 g. load.                                             .sup.4 Heat Shock  Highest temperature (25° C. increments) at whic     IX mandrel shows no cracks in 1 hour test.                                    .sup. 5 CutThrough  Crossed wires loaded with 1000 g. weight and              temperature increased at 5° C. per minute. Cutthrough temperature      is temperature at which wires fail 120 V.                                     .sup.6 Thermal Life  TEEE No. 57 Procedure, 1000 volt criterion on twiste     pairs.                                                                   

                  TABLE III                                                       ______________________________________                                        Weight Loss Data                                                              In Air Circulating Ovens - Approx. 1/4 g.                                     Film in 2.0" Diam. Aluminum Dish                                              Weight Loss at 250° C., %                                                                  Weight Loss at 200° C., %                                 10      40       80    10    60   120  400                             Example                                                                              days    days     days  days  days days days                            ______________________________________                                        1      16      30.5     43.5  3.5   8.9  14.6 21.6                            5      5.8     16.6     25.8  0.5   1.5  3.6  10.4                            3      1.8     8.1      15.4  -0.3* 0.3  1.2  4.1                             4      1.4     7.0      13.2  -0.7* 0.2  0.8  3.5                             11     13.0    29.5     43.0  No Data                                         12     8.5     20.5     25.5  No Data                                         8      6.6     15.0     18.8  0.5   1.3  2.6  6.1                             18     5.0     17.0     26.0  0.3   1.4  2.8  6.3                             20     11.0    22.5     27.5  0.5   2.2  5.0  12.8                            23     9.0     24.0     33.0  0.3   2.0  2.6  12.9                            ______________________________________                                         *Samples show actual weight gain.                                        

PRIOR ART POLYESTERS

The following examples are illustrations of the preparation of the priorart polyester coating compositions and the properties of wires insulatedwith such compositions.

EXAMPLE 1--Prior Art

    ______________________________________                                                                            Equivalent                                Ingredients                                                                            Grams    Moles    Equivalents                                                                            Percent                                   ______________________________________                                        EG        149.0   2.4      4.8      12.0                                      THEIC    1566.6   6.0      18.0     45.0                                      DMT      1552.0   8.0      16.0     40.0                                      IPT       84.0     0.785   1.18      2.95                                     ______________________________________                                    

The foregoing ingredients are charged to a 5-liter 4-neck flask equippedwith a motor-driven stirrer, nitrogen sparge tube, thermometer and steamcondenser.

The ingredients are heated to 160° C. with stirring and nitrogensparging and the temperature is increased at the rate of 15° C. per hourto a temperature of 205° C. At 205° C. the resinous mixture becomesviscous and thread-forming, and 3000 g. of cresylic acid and 1500 g. ofan aromatic hydrocarbon with a boiling range of 154° C. to 177° C.(Solvesso 100) are added.

The solution is diluted to coating viscosity with 1:1 by volume cresylicacid:Solvesso 100 and coated on #18 A.W.G. (0.040") copper wire to abuild of 2.8-3.2 mils with six passes through a 15-foot vertical towerat a hot spot temperature of 400° C. The properties listed in Table IIare very good except for heat shock resistance (passes 1X mandrel at175° C.) which is inferior to the polyester-amide-imides shown in thetable. The thermal life of Example 1 is also inferior to that of most ofthe polyester-amide-imide wire enamels listed in the table and theweight loss (Table III) is much higher.

EXAMPLE 2--Prior Art

    ______________________________________                                                                            Equivalent                                Ingredients                                                                            Grams   Moles      Equivalents                                                                           Percent                                   ______________________________________                                        EG       149.0   2.4        4.8     25.5                                      THEIC    522.2   2.0        6.0     31.8                                      DMT      776.0   4.0        8.0     42.4                                      IPT       3.0      0.01055   0.04    0.21                                     ______________________________________                                    

These ingredients are reacted in a 3-liter reaction vessel according tothe procedure of Example 1 to a thread-forming stage at a finaltemperature of 231° C. The resinous mixture is diluted first with 1500grams of cresylic acid and 750 grams of Solvesso 100, then to coatingviscosity with 1:1 cresylic acid:Solvesso 100 and coated on #18 A.W.G.wire. The properties listed in Table II show better flexibility andbaking range but lower abrasion resistance and heat shock resistancethan Example 1. The compositions of Examples 1 and 2 are used asblending materials in some of the examples hereinbelow.

TMA-THEIC BLOCK POLYESTER

The following examples are illustrative of the preparation of polymericamide-imide-esters of this invention and the properties of wireinsulated with such compositions. The block polyester is prepared fromTMA and THEIC, sometimes with the addition of EG. The amide-imidelinkages are derived from either MDA or MPD reacted with TMA.

EXAMPLE 3

    ______________________________________                                                                            Equivalent                                Ingredients                                                                            Grams    Moles    Equivalents                                                                            Percent                                   ______________________________________                                        PART A:                                                                       THEIC    2340.0   8.96     26.88    24.85                                     TMA       690.0   3.59     10.77     9.92                                     IPT       16.2    0.0571    0.228    0.23                                     PART B:                                                                       MDA      2680.0   13.5     27.0     25.00                                     TMA      4150.0   21.6     43.2     39.90                                     ______________________________________                                    

The Part A ingredients, together with 539 grams of m,p-cresol, arecharged to a 10-gallon reaction kettle equipped with motor-drivenstirrer, nitrogen sparge tube, thermometer and air condenser. The chargeis heated to 200° C. at a rate of 10° C. per hour and held at 200° C.until a thread-forming stage is reached. The reacted charge is dilutedwith 10,100 grams of m,p-cresol.

The MDA of Part B is then added. The TMA is added slowly over a periodof one hour. After the entire TMA addition, the temperature is increasedto 195° C. and held until a clear and thread-forming stage is reached.The product solution is diluted with 8630 grams of cresylic acid and6480 grams of Solvesso 100, then thinned further to a viscosity of 9poises at 25° C. with 1:1 cresylic acid:Solvesso 100. The solution iscoated on #18 A.W.G. wire at 17 ft./min. to 25 ft./min. in a 15 footvertical enameling tower at a hot spot temperature of 400° C.

The properties summarized in Table II show a much improved heat shockover Examples 1 and 2. Weight loss data in Table III show a much lowerweight loss than the polyesters.

EXAMPLE 4

    ______________________________________                                                                            Equivalent                                Ingredients                                                                            Grams    Moles    Equivalents                                                                            Percent                                   ______________________________________                                        PART A:                                                                       THEIC    174.0    0.667    2.0      19.65                                     TMA       42.7    0.222    0.666     6.54                                     IPT       1.5      0.0053  0.021     0.21                                     PART B:                                                                       MDA      297.7    1.5      3.0      29.50                                     TMA      432.5    2.25     4.5      44.10                                     ______________________________________                                    

The Part A ingredients, together with 50 grams of m,p-cresol are chargedto a 3 liter 4-neck flask equipped with a stirrer, nitrogen sparge tube,thermometer and air condenser. The charge is heated to 160°-190° C. at10° C./hour to a thread-forming stage. The MDA of Part B, together with705 gram of m,p-cresol is added to the reacted charge. The TMA is addedslowly over a one hour period at a reaction temperature of 160° C. Thetemperature is increased to 205° C. at 10° C./hour and held at 205° C.until a thread-forming resinous reaction product is obtained. Theproduct is diluted with 900 grams of m,p-cresol and 700 grams ofSolvesso 100. The solution is cooled and diluted further with 1:1 byvolume cresylic acid:Solvesso 100 to a viscosity of 9.0 poises. Coatingson #18 A.W.G. wire give the properties shown in Table II withoutstanding heat shock resistance. The weight loss of this material(Table III) is also outstandingly low.

EXAMPLE 5

    ______________________________________                                                                            Equivalent                                Ingredients                                                                            Grams    Moles    Equivalents                                                                            Percent                                   ______________________________________                                        PART A:                                                                       EG        44.4    0.715    1.430    10.8                                      THEIC    310.0    1.187    3.561    26.90                                     TMA      205.5    1.07     3.210    24.20                                     IPT       3.0      0.01055 0.042     0.32                                     ______________________________________                                        PART B:                                                                       MDA      212.0    1.07     2.14     16.15                                     TMA      350.0    1.43     2.86     21.60                                     ______________________________________                                    

The Part A ingredients, together with 100 grams of m,p-cresol, arecharged into a 3-liter 4-neck flash equipped with a motor-drivenstirrer, nitrogen sparge tube, thermometer and steam condenser.

The ingredients are heated in the range of 160°-196° C. at a rate of 15°C. per hour where a thread-forming stage is reached and the solution isdiluted with 650.0 grams of m,p-cresol. At this point the MDA of Part Bis added. The steam condenser is replaced by an air condenser and thetemperature is increased to 170°-190° C. while the TMA is added slowly.The reaction is continued at 200° C. until a thread-forming resinsolution is formed and 900 g. cresylic acid and 600 g. Solvesso 100 areadded. The solution is adjusted to a viscosity of 9.0 poises at 25° C.with 1:1 cresylic acid:Solvesso 100 and is coated on #18 A.W.G. wire at17 ft./min. to 25 ft./min. in a 15-foot vertical tower at a hot spottemperature of 400° C. The properties are listed in Table II.

EXAMPLE 6

    ______________________________________                                                                            Equivalent                                Ingredients                                                                            Grams    Moles    Equivalents                                                                            Percent                                   ______________________________________                                        PART A:                                                                       EG        54.9    0.883    1.766    13.20                                     THEIC    310.0    1.187    3.561    26.60                                     TMA      238.0    1.238    3.714    27.70                                     IPT       3.0      0.0106  0.042     0.31                                     PART B:                                                                       MPD       95.5    0.883    1.766    13.20                                     TMA      242.6    1.265    2.530    18.90                                     ______________________________________                                    

The Part A ingredients, together with 50.0 grams of m,p-cresol, areplaced in the reaction flask. With nitrogen sparging and an aircondenser the temperature is increased 160° C. to 190° C. at 15° C. perhour to a thread-forming stage where 784 g. m,p-cresol and the MPD ofPart B are added. The temperature is increased to 175° C. and the TMA isadded slowly over a period of four hours. A semi-solid resin solution isformed which becomes liquid and thread-forming after an additionalheating period of one hour at 190°-200° C. The resin solution is dilutedto 9 poises viscosity at room temperature with 1:1 by volume cresylicacid:Solvesso 100 and coated on #18 A.W.G. Wire. Properties listed inTable II show fair baking range and flex-reliability and very good heatshock, abrasion and cut through resistance along with very good thermallife.

EXAMPLE 7

    ______________________________________                                                                            Equivalent                                Ingredients                                                                            Grams    Moles    Equivalents                                                                            Percent                                   ______________________________________                                        PART A:                                                                       EG        88.8    1.43     2.86     21.2                                      THEIC    186.0     0.714   2.14     15.89                                     TMA      205.5    1.07     3.21     23.80                                     IPT       21.0     0.074    0.296    2.20                                     PART B:                                                                       MPD      114.6    1.06     2.12     15.70                                     TMA      275.0    1.43     2.86     21.20                                     ______________________________________                                    

The foregoing ingredients are employed to prepare another compositionfollowing the procedures outlines in Example 6. The charge is higher inethylene glycol, m-phenylenediamine, and isopropyl titanate catalyst andlower in THEIC than Example 6. The amide-imide portion in this Examplecontains 1.35 mols trimellitic anhydride per mol m-phenylenediamine. Theflexibility is reduced due to the high isopropyl titanate content butthe abrasion resistance is very good. The properties are summarized inTable II.

EXAMPLE 8

    ______________________________________                                                                            Equivalent                                Ingredients                                                                            Grams    Moles     Equivalents                                                                           Percent                                   ______________________________________                                        PART A:                                                                       EG       198.0    3.19       6.38   10.82                                     THEIC    1382.    5.29      15.87   26.82                                     TMA      915.     4.76      14.28   24.20                                     IPT      13.4      0.0472    0.189   0.32                                     PART B:                                                                       MPD      511.     4.73       9.46   16.08                                     TMA      1228.    6.38      12.76   21.65                                     ______________________________________                                    

The procedure of Example 6 is employed with the foregoing ingredients.The ethylene glycol and isopropyl titanate content are reduced and theTHEIC content is increased over that of Example 7. The molar ratio ofTMA/MPD in the amide-imide is 1.35. Improved cut through resistance,thermal life, and heat shock results with decreased abrasion resistance.The properties are summarized in Table II.

DMT-THEIC BLOCK POLYESTER

The following examples are illustrations of the preparation of polymericamide-imide-esters of this invention wherein the block polyester isprepared from DMT and THEIC, sometimes with the addition of EG. Theamide-imide linkages are provided by TMA and either MDA or MPD.

EXAMPLE 9

    ______________________________________                                                                            Equivalent                                Ingredients                                                                            Grams    Moles    Equivalents                                                                            Percent                                   ______________________________________                                        PART A:                                                                       EG        18.6    0.3      0.60      6.67                                     THEIC    196.0     0.75    2.25     25.00                                     DMT      194.1    1.0      2.00     22.22                                     IPT       10.5     0.037    0.148    1.64                                     PART B:                                                                       MDA      198.1    1.0      2.0      22.22                                     TMA      192.1    1.0      2.0      22.22                                     ______________________________________                                    

The Part A ingredients, together with 25.0 g. m,p-cresol and 13.0 g.xylene, are charged to a 2-liter 4-neck flask equipped with amotor-driven stirrer, nitrogen sparge tube, thermometer and steamcondenser.

The ingredients are heated at 160°-202° C. at a rate of 15° C. per hourwhere a thread-forming stage is reached and the solution is diluted with250.0 g. m,p-cresol. At this point the MDA of Part B dissolved in 200.0g. m,p-cresol is added. The stream condenser is replaced by an aircondenser and the temperature is increased 160°-180° C. over a period of3 hours while the TMA, suspended in 200 g. m,p-cresol, is added slowlyover the 3-hour period. The reaction is continued at 180° C. to finalreaction temperature of 200° C. over a period of 3 hours after which athread-forming resin solution is formed and 950 g. cresylic acid and 525g. Solvesso 100 are added. The resulting solution has a viscosity of 9.0poises at 25° C. and is coated on #18 A.W.G. wire at 17 ft./min. to 25ft./min. in a 15-foot vertical tower at a hot spot temperature of 400°C. The properties listed in Table II show fair flexibility, goodabrasion resistance, cut through temperature and thermal life. The heatshock resistance is excellent, passing a 1X mandrel at 225° C.

EXAMPLE 10

    ______________________________________                                                                            Equivalent                                Ingredients                                                                            Grams    Moles    Equivalents                                                                            Percent                                   ______________________________________                                        PART A:                                                                       THEIC    407.0    1.56     4.68     39.0                                      DMT      303.0    1.56     3.12     26.0                                      IPT       3.0      0.0106   0.042    0.35                                     PART B:                                                                       MPD      112.3    1.04     2.08     17.32                                     TMA      200.0    1.04     2.08     17.32                                     ______________________________________                                    

The Part A ingredients, together with 100 grams of m,p-cresol, arecharged to a 2-liter 4-neck flask equipped as heretofore described. Thereaction is conducted at 160°-195° C. at a rate of 10° C. per hour untila thread-forming stage is reached. The MDA of Part B together with 600grams of m,p-cresol are added. The TMA of Part B is added slowly overthe period of one hour. The reaction is continued at 200° C. until athread-forming stage is reached. The product is diluted with a mixtureof cresylic acid and Solvesso 100 (1:1, by volume) and, after cooling,adjusted with the mixture to a viscosity of 9.0 poises at 25° C. A heavybuild is applied to #18 A.W.G. wire in the tower heretofore described.The properties are summarized in Table II.

EXAMPLE 11

    ______________________________________                                                                            Equivalent                                Ingredients                                                                            Grams    Moles    Equivalents                                                                            Percent                                   ______________________________________                                        PART A:                                                                       EG        48.5    0.78     1.56     13.12                                     THEIC    305.0    1.17     3.51     24.6                                      DMT      353.5    1.82     3.64     30.70                                     IPT       3.0      0.0106   0.042    0.35                                     PART B:                                                                       MPD       84.5    0.78     1.56     13.12                                     TMA      150.0    0.78     1.56     13.12                                     ______________________________________                                    

The Part A ingredients, together with 20.0 grams of m,p-cresol and 10.0grams of xylene, are charged to a 2-liter reaction flask equipped asdescribed heretofore. When a thread-forming stage is reached, the Part Bingredients, together with 500 grams of cresylic acid are added, the TMAbeing added slowly. The final product (at a thread-forming stage) isdiluted with the 1:1 cresylic acid:Solvesso 100 mixture to a viscosityof 9 poises at 25° C. and coated, in accordance with proceduresheretofore described, onto #18 A.W.G. wire. The properties aresummarized in Tables II and III.

EXAMPLE 12

    ______________________________________                                                                            Equivalent                                Ingredients                                                                            Grams    Moles    Equivalents                                                                            Percent                                   ______________________________________                                        PART A:                                                                       EG        29.1    0.468    0.94      8.25                                     THEIC    237.0    0.911    2.73     23.90                                     DMT      242.0    1.245    2.49     21.80                                     IPT       3.0      0.0106   0.042    0.36                                     PART B:                                                                       MPD      140.5    1.30     2.60     22.80                                     TMA      250.0    1.30     2.60     22.80                                     ______________________________________                                    

The Part A ingredients, together with 20.0 grams of m,p-cresol and 10grams of xylene, are charged to a 4-neck, 3-liter reaction flaskequipped with motor stirrer, steam condenser, thermometer and nitrogensparge tube. The charge is heated through the range of 160°-215° C. at arate of 15° C. per hour and held at the maximum temperature until athread-forming stage is reached. At this point, the MPD of Part Bdissolved in 700 grams of m,p-cresol is added. The TMA is added slowlyover a period of one hour. The charge is heated to 205° C. at a rate of10° C. per hour and held at 205° C. until a thread-forming stage isreached. 300 grams of Solvesso 100 and 800 grams of m,p-cresol are addedto the reacted charge and the charge is cooled. A mixture of 1:1cresylic acid:Solvesso 100 is added to thin the solution to a viscosityof 9.0 poises at 25° C. The resulting solution is coated on #18 A.W.G.wire at 17 ft./min. to 25 ft./min. in a 15-foot vertical tower at a hotspot temperature of 400° C. The properties are listed in Table II and itis apparent therefrom that the thermal life of the insulation is verygood at 225° C. and 200° C. with and without silicone varnish.

EXAMPLE 13

    ______________________________________                                                                            Equivalent                                Ingredients                                                                            Grams    Moles    Equivalents                                                                            Percent                                   ______________________________________                                        PART A:                                                                       EG        19.4    0.312    0.624     5.50                                     THEIC    203.0    0.778    2.334    20.60                                     DMT      202.0    1.040    2.080    18.32                                     IPT       3.0      0.0106  0.042     0.37                                     PART B:                                                                       MPD      168.2    1.56     3.12     27.50                                     TMA      300.0    1.56     3.12     27.50                                     ______________________________________                                    

The foregoing ingredients were employed in accordance with theprocedures outlined in Example 12 hereinabove to produce wire enamelingcompositions and insulated electrical conductors. Part A was reacted to215° C. in the presence of 20.0 grams of m,p-cresol and 10.0 grams ofxylene. Part B was reacted to 205° C. with 600.0 grams of m,p-cresoladded with the MPD. The properties are summarized in Table II. It isapparent that the heat shock resistance has been markedly improved bythe increased amide-imide content. The thermal life is very good at 225°C. and 200° C. with and without silicone varnish. The flexibility andthe baking range in this example are beginning to decrease slightly dueto the high amide-imide content. Amide-imide contents appreciably higherthan that employed in this Example can be expected to yield very brittlecoatings.

Boiling Xylene Tests: Wire samples of Examples 11, 12 and 13 wereelongated 15%, wrapped on a 1X mandrel and placed in boiling xylene forone-half hour. They showed no cracking, whereas a wire sample of Example1 cracked badly when wrapped unelongated on a 1X mandrel and placed inboiling xylene for ten minutes. This is an important practical test forevaluating the resistance of an enamel to varnish dipping and bakingafter winding into equipment with automatic winding machines.

MIXED ACID-THEIC BLOCK POLYESTER

The following examples are illustrations of the preparation of polymericamide-imide-esters of this invention wherein the block polyester isprepared from a mixture of acid components such as DMT and TMA withTHEIC. The amide-imide linkages are provided by the TMA and the aromaticdiamine. It will become apparent from the following examples that themixed polyester may be prepared from an admixture of the acid componentsin a single reaction or that the mixed polyester is a result of aninitial reaction with one acid component and a subsequent reaction withanother acid component.

EXAMPLE 14

    ______________________________________                                                                            Equivalent                                Ingredients                                                                            Grams    Moles    Equivalents                                                                            Percent                                   ______________________________________                                        PART A:                                                                       EG        66.5    1.072    2.14     16.20                                     THEIC    248.0    0.949    2.85     21.55                                     DMT      155.5    0.802    1.60     12.10                                     TMA      102.7    0.535    0.61     12.20                                     IPT       3.0      0.0106   0.042    0.32                                     PART B:                                                                       MPD      114.6    1.06     2.12     16.02                                     TMA      275.0    1.43     2.86     21.60                                     ______________________________________                                    

The Part A ingredients, together with 50.0 grams of m,p-cresol, arecharged to a 3-liter 4-neck flask equipped with a motor-driven stirrer,nitrogen sparge tube, thermometer and steam condenser. The charge isheated to the range of 160°-215° C. at a rate of 15° C. per hour andheld at the upper temperature until a thread-forming stage is reached.At this point the MPD of Part B together with 750 grams of m,p-cresol isadded to the charge. The temperature is slowly increased over a periodof three hours to about 200° C. while the TMA of Part B is slowly added.The reaction is continued until another thread-forming stage is reached.The product is diluted with 900 grams of cresylic acid and 900 grams ofSolvesso 100 and adjusted to a viscosity of 9.0 poises at 25° C. Thiscoating composition or solution is coated on #18 A.W.G. wire at 17ft./min. to 25 ft./min. in a 15-foot vertical tower at a hot spottemperature of 400° C. The excellent range of properties provided bythis composition are listed in Table II herein.

EXAMPLE 15

    ______________________________________                                                                            Equivalent                                Ingredients                                                                            Grams    Moles    Equivalents                                                                            Percent                                   ______________________________________                                        PART A:                                                                       EG       71.4     1.155    2.31     21.00                                     THEIC    25.0     0.096    0.28      2.54                                     DMT      168.0    0.866    1.73     15.71                                     IPT       4.0      0.0141   0.056    0.51                                     PART B:                                                                       MPD      93.6     0.866    1.73     15.71                                     TMA      187.2    0.974    1.95     17.70                                     PART C:                                                                       THEIC    127.1    0.49     1.47     13.35                                     TMA      93.6     0.49     1.47     13.35                                     ______________________________________                                    

The foregoing Part A ingredients together with 20.0 grams of m,p-cresoland 10.0 grams of xylene are charged to a 3-liter 4-neck flask equippedwith a motor-driven stirrer, nitrogen sparge tube, thermometer and steamcondenser. The ingredients are heated to a temperature of 160°-240° C.at a rate of about 15° C. per hour and held at that temperature until athread-forming stage is reached. The MPD of Part B together with 425.0grams of m,p-cresol are added and the TMA of Part B is added slowly asthe temperature is again slowly raised to about 200° C. The reaction iscontinued at that temperature until another thread-forming stage isreached. At that point, the Part C ingredients together with 100.0 gramsof m,p-cresol are added and the temperature is again raised to about200° C. and the reaction is continued until another thread-forming stageis reached. The reacted mass is finally diluted with 600 grams ofcresylic acid and 400 grams of Solvesso 100, the viscosity beingadjusted with a 1:1 cresylic acid:Solvesso 100 admixture to provide avalue of 9 poises at 25° C. The composition is coated on #18 A.W.G. wireat 17 ft./min. to 25 ft./min. in a 15-foot vertical tower at a hot spottemperature of 400° C. The properties are summarized in Table II and itis apparent that the composition has provided an insulation with anexcellent coating range, flexibility, and heat shock resistance togetherwith fair cut-through resistance and thermal life.

EXAMPLE 16

    ______________________________________                                                                            Equivalent                                Ingredients                                                                            Grams    Moles    Equivalents                                                                            Percent                                   ______________________________________                                        PART A:                                                                       EG        24.2    0.39     0.78      7.10                                     THEIC    152.0    0.606    1.82     16.51                                     DMT      168.1    0.866    1.73     15.72                                     IPT       3.0      0.0106  0.04      0.37                                     PART B:                                                                       MPD       93.6    0.866    1.73     15.72                                     TMA      187.0    0.974    1.95     17.72                                     PART C:                                                                       THEIC    127.0    0.487    1.47     13.38                                     TMA       93.6    0.487    1.47     13.38                                     ______________________________________                                    

The ingredients of Part A together with 20.0 grams of m,p-cresol and10.0 grams of xylene are charged to a reaction flask equipped with amotor-driven stirrer, nitrogen sparge tube, thermometer and steamcondenser. The charge is heated through the range of 160° to 200° C. ata rate of 15° C. per hour and held at 200° C. until a thread-formingstage is reached. The MPD of Part B together with 775 grams ofm,p-cresol are added and an air condenser is substituted for the steamcondenser. After heating to 178° C., the TMA of Part B is added slowlyover a period of four hours and the temperature is increased to 200° C.to second thread-forming stage. The TMA and THEIC together with 100.0grams of m,p-cresol are added and the reaction is continued at 195° C.until another thread-forming stage is reached. The resinous product isdiluted to 9.0 poises at 25° C. with a mixture of 1:1 cresylicacid:Solvesso 100, by volume, and coated on #18 A.W.G. wire at 17ft/min. to 25 ft./min. in a 15-foot vertical tower at a hot spottemperature of 400° C. The properties listed in Table II show a fairbaking range with good flexibility, excellent abrasion resistance,excellent cut-through resistance, excellent heat shock and excellentthermal stability.

COLD BLENDS OF POLYMERIC SOLUTIONS

The following examples illustrate cold blends of solutions heretoforedescribed. The blends contain from about 20 to 60 percent by weight on asolids basis of a polyester resin derived from DMT, THEIC and EGcatalyzed by IPT. The polyester of Example 1 is an example of apolyester resin that may be employed in the cold blended compositions ofthis invention. A minor proportion (10 to 20 percent on a solids weightbasis) of a polyisocyanate, particularly the end-blocked trimer oftolylene diisocyanate and/or a minor proportion (1 to 6 percent on asolids weight basis) of IPT may be added to the cold blends. It will beapparent that the properties of compositions made in accordance withthis aspect of the invention exhibit the best thermal life propertiesand a combination of properties that are not attainable withcompositions obtained in a single reaction. Heat shock, cut-through,flexibility and baking range are particularly outstanding properties.

EXAMPLE 17

The polyester of Example 1 and the polymeric amide-imide-ester ofExample 5 are blended together in amounts to provide a 30:70 weightproportional of Example 1:Example 5 solids and diluted to a viscosity of9.0 poises at 25° C. with a 1:1 by volume mix of cresylic acid andSolvesso 100. The blended composition is coated on #18 A.W.G. copperwire in a 15-foot vertical tower at a hot spot temperature of about 400°C. to a build of 2.8 to 3.2 mils. The properties are summarized 1 inTable II. The sum of the equivalent percentages of each of theingredients present in the polymeric amide-imide-ester and the polyester(based on the total blend) are summarized in Table IV.

EXAMPLE 18

The polyester of Example 1 and the polymeric amide-imide-ester ofExample 3 are blended together in amounts to provide a 30:70 weightproportion of Example 1:Example 3 solids and diluted to a viscosity of9.0 poises at 25° C. with a 1:1 by volume mix of cresylic acid andSolvesso 100. The blended composition is coated on #18 A.W.G. copperwire in a 15-foot vertical tower at a hot spot temperature of 400° C. toa build of 2.8 to 3.2 mils. The properties are summarized in Table II.The sum of the equivalent percentages of each of the ingredients presentin the polymeric amide-imide-ester and the polyester (based on the totalblend) are summarized in Table IV.

EXAMPLE 19

The polyester of Example 1 and the polymeric amide-imide-ester ofExample 4 are blended together in amounts to provide a 30:70 weightproportion of Example 1:Example 4 solids and diluted to a viscosity of9.0 poises at 25° C. with a 1:1 by volume mix of cresylic acid andSolvesso 100. The blended composition is coated on #18 A.W.G. copperwire in a 15-foot vertical tower at a hot spot temperature of about 400°C. to a build of 2.8 to 3.2 mils. The properties are summarized in TableII. The sum of the equivalent percentages of each of the ingredientspresent in the polymeric amide-imide-ester and the polyester (based onthe total blends) are summarized in Table IV.

EXAMPLE 20

The polyester of Example 1, the polymeric amide-imide-ester of Example15 and a portion of IPT are blended together in amounts to provide a30:64:6 weight proportion of Example 1:Example 15:IPT solids and dilutedto a viscosity of 9.0 poises at 25° C. with a 1:1 by volume mix ofcresylic acid and Solvesso 100. The blended composition is coated on #18A.W.G. copper wire in a 15-foot vertical tower at a hot spot temperatureof about 400° C. to a build of 2.8 to 3.2 mils. The properties aresummarized in Table II. The sum of the equivalent percentages of each ofthe ingredients present in the total blend are summarized in Table IV.

EXAMPLE 21

The polyester of Example 1 and the polymeric amide-imide-ester ofExample 8 are blended together in amounts to provide a 50:50 weightproportion of Example 1:Example 8 solids and diluted to a viscosity of9.0 poises at 25° C. with a 1:1 by volume mix of cresylic acid andSolvesso 100. The blended composition is coated on #18 A.W.G. copperwire in a 15-foot vertical tower at a hot spot temperature of about 400°C. to a build of 2.8 to 3.2 mils. The properties are summarized in TableII. The sum of the equivalent percentages of each of the ingredients inthe polymeric amide-imide-ester and the polyester (based on the totalblend) are summarized in Table IV.

EXAMPLE 22

The polyester of Example 1 and the polymeric amide-imide-ester ofExample 8 are blended together in amounts to provide a 30:70 weightproportion of Example 1:Example 8 solids and diluted to a viscosity of9.0 poises at 25° C. with a 1:1 by volume mix of cresylic acid andSolvesso 100. The blended composition is coated on #18 A.W.G. copperwire in a 15-foot vertical tower at a hot spot temperature of about 400°C. to a build of 2.8 to 3.2 mils. The properties are summarized in TableII. The sum of the equivalent percentages of each of the ingredients inthe polymeric amide-imide-ester and the polyester (based on the totalblend) are summarized in Table IV.

EXAMPLE 23

The polyester of Example 1, the polymeric amide-imide-ester of Example 8and the phenol blocked trimer of tolylene diisocyanate are blendedtogether in amounts to provide a 40:55:5 weight proportion of Example1:Example 8:trimer solids and diluted to a viscosity of 9.0 poises at25° C. with a 1:1 by volume mix of cresylic acid and Solvesso 100. Theblended composition is coated on #18 A.W.G. copper wire in a 15-footvertical tower at a hot spot temperature of about 400° C. to a build of2.8 to 3.2 mils. The properties are summarized in Table II. The sum ofthe equivalent percentages of each of the ingredients in the polymericamide-imide-ester and the polyester (based on the total blend) aresummarized in Table IV.

EXAMPLE 24

The polyester of Example 1 and the polymeric amide-imide-ester ofExample 8 and the hereinabove described trimer are blended together inamounts to provide a 40:50:10 weight proportion of Example 1:Example8:trimer solids and diluted to a viscosity of 9.0 poises at 25° C. witha 1:1 by volume mix of cresylic acid and Solvesso 100. The blendedcomposition is coated on #18 A.W.G. copper wire in a 15-foot verticaltower at a hot spot temperature of about 400° C. to a build of 2.8 to3.2 mils. The properties are summarized in Table II. The sum of theequivalent percentages of each of the ingredients in the polymericamide-imide-ester and the polyester (based on the total blend) aresummarized in Table IV.

EXAMPLE 25

The polyester of Example 1, the polymeric amide-imide-ester of Example 3and the heretofore described blocked trimer are blended together inamounts to provide a 40:50:10 weight proportion of Example 1:Example3:trimer solids and diluted to a viscosity of 9.0 poises at 25° C. witha 1:1 by volume mix of cresylic acid and Solvesso 100. The blendedcomposition is coated on #18 A.W.G. copper wire in a 15-foot verticaltower at a hot spot temperature of about 400° C. to a build of 2.8 to3.2 mils. The properties are summarized in Table II. The sum of theequivalent percentages of each of the ingredients in the polymericamide-imide-ester and the polyester (based on the total blends) aresummarized in Table IV.

EXAMPLE 26

The polyester of Example 1, the polymeric amide-imide-ester of Example 8and the heretofore described blocked trimer are blended together inamounts to provide a 20:70:10 weight proportion of Example 1:Example8:trimer solids and diluted to a viscosity of 9.0 poises at 25° C. witha 1:1 by volume mix of cresylic acid and Solvesso 100. The blendedcomposition is coated on #18 A.W.G. copper wire in a 15-foot verticaltower at a hot spot temperature of about 400° C. to a build of 2.8 to3.2 mils. The properties are summarized in Table II. The sum of theequivalent percentages of each of the ingredients in the polymericamide-imide-ester and the polyester (based on the total blend) aresummarized in Table IV.

It should be apparent from a comparison of the property summaries inTable II that the heat shock resistance of Example 5 is decreasedslightly when the Example 1 polyester is blended therewith to form theblended composition of Example 17. However, a most striking andunexpected increase in thermal life at 225° C. is obtained with theExample 17 composition compared to that obtained with the compositionsof either Example 1 or Example 5. The improved thermal life is againnoted in the blend of Example 18 where excellent flexibility, abrasionresistance, heat shock resistance, cut-through and thermal life areobtained. Example 19, which contains 70% of the very high amide-imideratio resin of Example 4 shows an excellent baking range with excellentproperties except that cut-through is slightly lower and the coatings donot show the marked improvement in thermal life that is apparent in thecompositions of Examples 17 and 18. The high IPT content of Example 20contributes to a desirable coating "slickness" and very high adhesion ofthe coating to the copper wire. The composition of Example 21 isexcellent in every property except heat shock, the latter still beingadequate for most applications. In Example 22, the baking range andflexibility are not as good as in Example 21 but the heat shock isimproved and the thermal life, both with and without silicone varnish,is outstanding.

Examples 23 through 26 illustrate the effect of the addition of minorproportions of a trifunctional blocked isocyanate having the formula:##STR1## to the blends of the polymeric amide-imide-esters andpolyesters. Example 23, which contains five percent of the trifunctionalblocked isocyanate, has a good baking range and otherwise exhibits verygood properties. The increased blocked isocyanate content of Example 24results in a slightly decreased flexibility as compared to Example 23.Example 26, which contains only 20% of a polyester in the blend, has alower baking range and poorer thermal life at 225° C. but has betterheat shock properties. Example 25, because of the higher amide-imidecontent in the polymeric amide-imide-ester portion, has a better heatshock but a lower thermal life compared to Example 24.

The equivalent percentages of the ingredients employed in Examples 17through 26 are summarized in the following Table.

                                      TABLE IV                                    __________________________________________________________________________    Equivalent Percentages of Ingredients                                         Example                                                                            EG  THEIC                                                                              MPD MDA TMA DMT IPT Other                                       __________________________________________________________________________    17   11.19                                                                             32.84                                                                              --  10.81                                                                             30.60                                                                             13.28                                                                             1.19                                                                              --                                          18    4.00                                                                             31.59                                                                              --  16.65                                                                             33.23                                                                             13.38                                                                             1.12                                                                              --                                          19    5.87                                                                             31.98                                                                              --  15.08                                                                             25.94                                                                             19.60                                                                             1.56                                                                              --                                          20   17.45                                                                             22.95                                                                              10.70                                                                             --  21.04                                                                             21.54                                                                             5.55                                                                              --                                          21   11.40                                                                             35.52                                                                               8.37                                                                             --  23.92                                                                             19.20                                                                             1.59                                                                              --                                          22   11.13                                                                             32.03                                                                              11.52                                                                             --  32.95                                                                             11.31                                                                             1.06                                                                              --                                          23   11.26                                                                             34.01                                                                               9.59                                                                             --  27.35                                                                             16.00                                                                             1.37                                                                              0.98                                        24   11.06                                                                             33.92                                                                               9.02                                                                             --  25.85                                                                             16.60                                                                             1.40                                                                              2.05                                        25    5.66                                                                             33.76                                                                              --  12.60                                                                             25.12                                                                             18.90                                                                             1.50                                                                              2.39                                        26   10.79                                                                             30.05                                                                              12.45                                                                             --  35.58                                                                              8.12                                                                             0.85                                                                              2.06                                        __________________________________________________________________________

HYDROLYTIC STABILITY

Wire samples of Examples 1, 3, 5, 18, 22 and 23 were all wrapped onmandrels varying in size from one to four times the diameter of the 18A.W.G. wire and sealed in separate glass tubes with several drops ofwater. The tubes were placed in a 150° C. oven and observedperiodically. The samples of Example 1 cracked badly after 20 hours onall mandrel sizes. All the other samples were still free of cracks onall of the mandrels after one week at 150° C. This test illustrates thesuperior resistance of the compositions of this invention to moisture.

BLENDS CONTAINING A POLYESTER AND A NOVEL ESTER-URETHANE-ISOCYANATEEXAMPLE 27

    ______________________________________                                                                              Overall                                                         Equiv-                                                                              Equivalent                                                                            Blend Equiv.                            Ingredients                                                                           Grams   Moles   alents                                                                              Percent Percent                                 ______________________________________                                        Polymeric Amide-Imide-Ester:                                                  PART A:                                                                       EG      155.4   2.51    5.02  15.91   6.88                                    TMA     205.5   1.07    3.21  10.20   4.40                                    IPT      21.0    0.074  0.30   0.95   0.41                                    PART B:                                                                       MPD     568.8   5.26    10.52 33.40   14.42                                   TMA     1198.5  6.23    12.46 39.50   17.05                                   ______________________________________                                    

The Part A ingredients, together with 45.0 grams of m,p-cresol arecharged to a 5-liter, 4-neck reaction flask equipped with a motor-drivenstirrer, an air condenser, a thermometer and a nitrogen sparge tube. Thecharge is rapidly heated to 160° C. and then to 195° C. at a rate of 15°C. per hour to form a thread-forming resin. At this point, the MPD ofPart B together with 2500 grams of m,p-cresol are added. The temperatureis increased to 170° C. and the TMA of Part B is added slowly over a twohour period while the temperature is maintained between 170° to 190° C.The temperature is then increased to about 205° C. for about four hoursuntil a thread-forming resin solution is formed. The product is dilutedwith 2580 grams of cresylic acid and 778 grams of Solvesso 100.

Polyester:

    ______________________________________                                        EG      235.0     3.79      7.58   25.50 10.38                                THEIC   825.0     3.16      9.48   31.80 12.98                                DMT     1225.0    6.32      12.64  42.50 17.31                                IPT     4.7       0.0166    .046    0.15  0.21                                ______________________________________                                    

The foregoing ingredients, together with 78.9 grams of m,p-cresol and39.5 grams of xylene, are reacted together in accordance with theprocedure outlined in Example 2 hereinabove to form a polyester. Theproduct is diluted with 2440 grams of cresylic acid and 1705 grams ofSolvesso 100.

Ester-Urethane-Isocyanate:

    ______________________________________                                        THEIC    364.0    1.395   4.18    37.40                                                                              5.73                                   DMT      135.5    0.698   1.40    12.51                                                                              1.92                                   IPT       2.1      0.0074 0.03     0.27                                                                              0.04                                   TDI      486.0    2.79    5.58    49.90                                                                              7.64                                   ______________________________________                                    

The THEIC, DMT and IPT are charged to a 3-liter reaction flask equippedwith stirrer, nitrogen sparging and steam condenser. The charge israpidly heated to 160° C. and then to 220° C. at a rate of 15° C. perhour. At 220° C., the solution is diluted with 576 grams of cresylicacid and is cooled to 60° C. A solution of the TDI (Nacconate 80)dissolved in 603 grams of cresylic acid is added to reaction flask andthe temperature is rapidly increased to 125° C. After one hour at 125°C., 418 grams of cresylic acid and 418 grams of Solvesso 100 are addedto the reaction flask.

Addition:

    ______________________________________                                        IPT    47.2       0.166  0.66    100.0                                                                              0.90                                    ______________________________________                                    

The three resinous product solutions and the additionalisopropyltitanate dissolved in 94 grams of cresylic acid are blendedtogether. The resulting solution contains 29.5% solids and has aviscosity of 9.5 poises at 25° C. When coated on #18 A.W.G. wire, thecomposition exhibits an excellent baking range with excellentflexibility, abrasion resistance and heat shock resistance together withgood cut-through temperature and thermal life. The properties aresummarized in Table II.

Wire samples of Example 27 were elongated 15%, wrapped on a mandrelhaving a diameter equal to the diameter of the wire and placed inboiling xylene for one-half hour. No cracking occurred. A spool of theExample 27 wire was wound into fractional horsepower motor stators usingautomatic winding equipment. The wires were carefully removed from thesestators and tested at 110 volts for flaws in a salt water bath. A verylow number of flaws, eight flaws per 100 feet of wire, were found.Similar tests on a commercial Formvar wire enamel showed twenty flawsper 100 foot of wire.

A sample of the Example 27 wire removed from the stators was placed inboiling xylene for one-half hour and showed no flaws. A commercialcross-linked polyester coated wire, having a thermoplastic polyesterovercoat, was similarly wound and removed from stators and tested inboiling xylene for one-half hour. The commercial material showedfrequent spots of cracking and pealing.

BLENDS CONTAINING FLEXIBILIZED POLYESTER EXAMPLE 28

The composition for this Example was a blend identical to that describedin Example 27 except that 20% of the DMT of the polyester was replacedby an equimolar quantity of sebacic acid. The properties are summarizedin Table II. It should be noted that the flexibility and heat shock areparticularly good.

EXAMPLE 29

The composition for this Example was a blend identical to that describedin Example 27 except that 1,5-pentanediol was substituted for theethylene glycol of the polyester. The excellent flexibility provided bythis composition is accompanied by a lower cut-through temperature andlower thermal life. The properties are summarized in Table II.

EXAMPLE 30

The composition for this Example was a blend identical to that describedin Example 27 except that neopentyl glycol was substituted for theethylene glycol of the polyester. The excellent flexibility obtainedwith this composition is accompanied by a slightly lower cut-throughresistance and a good thermal life. The properties are summarized inTable II.

EXAMPLE 31

The composition for this Example was a blend identical to that describedin Example 27 except that 1,4-cyclohexanedimethane was substituted forthe ethylene glycol of the polyester. Some loss in flexibility andcut-through resistance is apparent. The properties are summarized inTable II.

EXAMPLE 32

The composition for this Example was a blend identical to that describedin Example 27 except that hexamethylene glycol was substituted for theethylene glycol of the polyester. The substitution has little effect onthe properties except for a somewhat reduced abrasion resistance. Theproperties are summarized in Table II.

EXAMPLE 33

The composition for this Example was a blend identical to that describedin Example 27 except that 1,4-butanediol was substituted for theethylene glycol of the polyester. The abrasion resistance andcut-through temperature was reduced with no improvement in flexibility.The properties are summarized in Table II.

EXAMPLE 34

The composition for this Example was a blend identical to that describedin Example 27 except that 20% of the DMT of the polyester was replacedby an equimolar quantity of adipic acid. The abrasion resistance andcut-through resistance was decreased and no improvement in flexibilitywas noted. The properties are summarized in Table II.

EXAMPLE 35

The composition for this Example was a blend identical to that describedin Example 27 except that 20% of the DMT of the polyester was replacedby an equimolar quantity of azelaic acid. The abrasion resistance andcut-through resistance was decreased and no improvement in flexibilitywas noted. The properties are summarized in Table II.

BLENDS CONTAINING PHENOLIC RESIN

The following examples illustrate the benefits that are derived fromincluding a phenolic resin as a component in the composition blends ofthis invention.

EXAMPLE 36

Phenolic Resin:

    ______________________________________                                        Ingredients        Grams   Moles                                              ______________________________________                                        Cresylic Acid      844.0   7.8                                                Formaldehyde - 37% 560.0   6.21                                               Triethanolamine     10.0                                                      ______________________________________                                    

A suitable phenolic resin is prepared by refluxing a charge of theforegoing ingredients at 98° C. with stirring, for 90 minutes. Thetemperature is decreased to 50° C. A vacuum (30-50 mm. Hg) is appliedfor about 3 hours. The temperature is increased to 100° C. during thisperiod until a sample of the resin diluted with an equal weight ofcresylic acid has a Gardner viscosity of S to U. At this point, the heatis turned off and 800 g. cresylic acid is added.

Two hundred grams of the phenolic resin solution (100 grams solids) and6,340 grams of the total blend of Example 27 (1900 grams solids) wereblended together and applied to #18 A.W.G. wire. The properties aresummarized in Table II. The very good cut through resistance andadhesion should be noted.

EXAMPLE 37

    ______________________________________                                                                            Equivalent                                Ingredients                                                                            Grams    Moles    Equivalents                                                                            Percent                                   ______________________________________                                        Polymeric Amide-Imide-Ester:                                                  PART A:                                                                       EG       129.2    2.08     4.16     13.37                                     TMA      171.0    0.888    2.66      8.52                                     IPT       17.3    0.061    0.24      0.77                                     PART B:                                                                       MPD      474.0    4.38     8.76     28.10                                     TMA (1)  821.0    4.27     8.54     27.40                                     TMA (2)  179.0    0.931    1.86      5.96                                     PART C:                                                                       TMA      117.0    0.608    1.22      3.92                                     THEIC    318.0    1.22     3.66     11.75                                     ______________________________________                                    

The Part A ingredients along with 36.6 g. cresylic acid are charged to a5-liter, 4-neck reaction flask equipped with a motor-driven stirrer, aircondenser, thermometer and a nitrogen sparge tube. The charge is heatedin the range of 160° to 195° C. at a rate of 10° C. per hour until aBall and Ring Softening Temperature of 60° C. is reached. At this point,the MPD and the TMA (1) of Part B together with 2,080 grams of cresylicacid is added to the charge. The reaction is continued at 170° to 195°C. until a clear solution is obtained. At this point, the TMA (2) isadded and the reaction is continued at 190° to 205° C. to a Ball andRing Softening Temperature of 60° C. At this point, the TMA of Part Ctogether with 666.0 grams of cresylic acid are added and the reaction iscontinued for one-half hour at 190° C. The THEIC of Part C is added andthe reaction is continued at 190° to 205° C. to a Ball and RingSoftening Temperature of 65° C. The product is diluted with 2,070.0grams of cresylic acid and 1,155.0 grams of Solvesso 100. The productsolution has a weight of about 7,850.0 grams and the solids content(determined by heating a 1.0 gram sample of the solution for one-halfhour at 200° C.) is 28.1%.

Polyester:

This component is identical to the polyester of Example 2 with the samequantity charge. The same ingredients in the same proportions as inExample 2 are reacted to a Ball and Ring Softening Temperature of 105°C. and the product yields 3560 grams of solution at 31.0% solids, whenthe final solvent addition is a total of 1390 grams of cresylic acid and972 grams of Solvesso 100.

Ester-Urethane-Isocyanate:

This component is identical to the ester-urethane-isocyanate of Example27. The solution contains 35.6% solids and weighs 2,965.0 grams.

Phenolic Resin:

    ______________________________________                                        Ingredients        Grams   Moles                                              ______________________________________                                        m,p-cresol         2870    26.6                                               Formaldehyde - 40% 1520    20.3                                               Triethanolamine     50     0.336                                              Salicylic Acid      50     0.362                                              ______________________________________                                    

The m,p-cresol, formaldehyde and triethanolamine are refluxed at 99° C.for 80 minutes and the salicylic acid is added to the charge. The refluxcondenser is removed and the pressure is reduced to two inches ofmercury and the reaction is continued at 40° to 60° C. until the resinhas a viscosity of 20 to 60 poises at 25° C. The resin is thinned with3,390.0 grams of cresylic acid. The yield is 6,700.0 grams of solutionat 35.5% solids.

The foregoing solutions, together with 2.5 grams of IPT and 5.0 grams ofcresylic acid, were blended together in the proportions indicated belowto provide a blended solution having a viscosity of 8.0 poises and a31.0% solids content.

Blended Composition:

    ______________________________________                                        Ingredients        Grams of Solution                                          ______________________________________                                        Polymeric Amide-Imide-Ester                                                                      142.2                                                      Polyester          106.0                                                      Ester-Urethane-Isocyanate                                                                         56.2                                                      Phenolic Resin      13.0                                                      IPT                 2.5                                                       ______________________________________                                    

When coated to a heavy build on 18 A.W.G. wire, the foregoing blendedcomposition had excellent properties that are summarized in Table II.The coated wires of this example also had a particularly outstandingEmerson Scrape resistance.

BLENDS CONTAINING POLYMERIC AMIDE-ESTER EXAMPLE 38

Polymeric Amide-Ester:

    ______________________________________                                        Ingredients     Grams   Moles                                                 ______________________________________                                        EG              134.3   2.16                                                  THEIC           470.0   1.8                                                   MPD              51.9   0.48                                                  DMT             776.0   4.0                                                   IPT              3.0     0.0106                                               ______________________________________                                    

The foregoing ingredients are charged into a 4-neck, 3-liter flaskequipped with motor-stirrer, nitrogen sparge tube, steam condenser andthermometer. The temperature is rapidly increased to 160° C., then to230° C. at a rate of 15° C. per hour to a final Ball and Ring SofteningTemperature of 109° C. The product is diluted with 1500 grams ofcresylic acid and 1250 grams of Solvesso 100. The solution contains29.8% solids.

The foregoing polymeric amide-ester is employed as a component in ablended composition that is identical to that described in Example 37except that 109.0 grams of the polymeric amide-ester solution replacesthe 106.0 grams of polyester solution. Excellent results are obtained on#18 A.W.G. wire as is apparent from the summary of properties in TableII.

EXAMPLE 39

Polymeric Amide-Ester:

    ______________________________________                                        Ingredients     Grams   Moles                                                 ______________________________________                                        EG              134.3   2.16                                                  THEIC           470.0   1.8                                                   EDA              28.8   0.48                                                  DMT             776.0   4.0                                                   IPT              3.0     0.0106                                               ______________________________________                                    

The foregoing ingredients are reacted to a Ball and Ring SofteningTemperature of 106° C. in a method identical to that described inExample 38. The product contained 29.0% solids.

The polymeric amide-ester of this example is employed as a component ina blended composition identical to that described in Example 37 exceptthat 113 grams of this polymeric amide-ester replaces the 106.0 gramspolyester. The excellent results obtained with a heavy build on #18A.W.G. wire is apparent from the properties summarized in Table II.

BLENDS CONTAINING PLURAL POLYMERIC AMIDE-IMIDE-ESTERS EXAMPLE 40

Polymeric Amide-Imide-Ester (A):

This component is identical to the polymeric amide-imide-ester describedin Example 37.

Polymeric Amide-Imide-Ester (B):

    ______________________________________                                        Ingredients        Grams   Moles                                              ______________________________________                                        Polymeric Amide-Imide                                                                            483.0                                                      Ester (A) Solution                                                            EG                 134.3   2.16                                               THEIC              470.0   1.8                                                DMT                683.0   3.52                                               IPT                 3.0     0.0106                                            ______________________________________                                    

The foregoing ingredients are charged into a 5-liter, 4-neck reactionflask equipped with a motor-driven stirrer, vertical steam condenser,thermometer and nitrogen sparge tube. The charge is rapidly heated to160° C., then to 205° C. at a rate of 15° C. per hour. At 205° C., aBall and Ring Softening Temperature of 84° C. is reached and 1300.0grams of resin grade cresylic acid and 990.0 grams of Solvesso 100 areadded. The product solution weighs 3,714.0 grams and contains 32.0%solids.

Ester-Urethane Isocyanate:

This component is identical to the ester-urethane isocyanate describedin Example 37.

Phenolic Resin:

This component was identical to the phenolic resin described in Example37.

The foregoing components are blended together to form an enamelingcomposition according to the following formula.

Blended Composition:

    ______________________________________                                        Ingredients           Grams                                                   ______________________________________                                        Polymeric Amide-Imide-Ester (A)                                                                     713.0                                                   Polymeric Amide-Imide-Ester (B)                                                                     703.0                                                   Ester Urethane Isocyanate                                                                           335.0                                                   Phenolic Resin         76.5                                                   IPT (In 30 grams Cresylic Acid)                                                                      15.0                                                   ______________________________________                                    

The polymeric amide-imide-ester (B) is more compatible with the othercomponents of the blend than the polyester of Example 37. The blendedcomposition of this example exhibits a wider baking range (from 17 to 40ft./min. versus 17 to 32 ft./min. for Example 37) and has excellentproperties when coated on #18 A.W.G. wire to a heavy build. Theproperties are summarized in Table II.

EXAMPLE 41

Polymeric Amide-Imide-Ester (A):

This component is identical to the polymeric amide-imide-ester describedin Example 37.

Polymeric Amide-Imide-Ester (B):

    ______________________________________                                        Ingredients        Grams   Moles                                              ______________________________________                                        Polymeric Amide-Imide-                                                                           966.0   --                                                 Ester (A)                                                                     EG                 134.3   2.16                                               THEIC              470.0   1.8                                                DMT                683.0   3.52                                               IPT                 3.0     0.0106                                            ______________________________________                                    

The foregoing ingredients are charged to a vessel equipped as describedin Example 40 and rapidly heated to 160° C., thereafter to 195° C. at arate of 15° C. per hour. At 195° C. a Ball and Ring SofteningTemperature of 75° C. is obtained and the product solution is dilutedwith 1300 grams of resin grade cresylic acid and 990 grams of Solvesso100. The solution weighs 4200 grams and contains 30.8% solids.

Ester-Urethane-Isocyanate:

This component is identical to the ester-urethane-isocyanate describedin Example 37.

Phenolic Resin:

This component is identical to the phenolic resin described in Example37.

Blended Composition:

    ______________________________________                                        Component             Grams                                                   ______________________________________                                        Polymeric Amide-Imide-Ester (A)                                                                     654.                                                    Polymeric Amide-Imide-Ester (B)                                                                     820.0                                                   Ester-Urethane-Isocyanate                                                                           335.                                                    Phenolic Resin        76.5                                                    IPT (In 30 grams Cresylic Acid)                                                                     15.0                                                    ______________________________________                                    

The blended composition of this Example gives good properties over awide baking range when coated to a heavy build on #18 A.W.G. wire butthe baking range is somewhat narrower than that obtained with theblended composition of Example 40. The properties are summarized inTable II.

EXAMPLE 42

Polymeric Amide-Imide-Ester (A):

This component is identical to the polymeric amide-imide-ester describedin Example 37.

Polymeric Amide-Imide-Ester (B):

    ______________________________________                                        Ingredients     Grams   Moles                                                 ______________________________________                                        EG              134.3   2.16                                                  THEIC           470.0   1.8                                                   MPD              51.9   0.48                                                  TMA              92.3   0.48                                                  DMT             683.0   3.52                                                  IPT              3.0     0.0106                                               ______________________________________                                    

The foregoing ingredients (the IPT being added together with 50.0 gramsof resin grade cresylic acid and 25.0 grams of xylol) are charged to aflask equipped as described in the previous examples. The charge israpidly heated to 160° C. and then to 225° C. at a rate of 15° C. perhour. A thread-forming stage is reached at the upper temperature and1500 grams of resin grade cresylic acid and 1080 grams of Solvesso 100are added. A solution containing 31.3% solids is obtained.

Ester-Urethane-Isocyanate:

This component is identical to the ester-urethane-isocyanate describedin Example 37.

Phenolic Resin:

This component is identical to the phenolic resin described in Example37.

The foregoing components are blended together in the proportionsindicated hereinbelow. The blend composition is coated on #18 A.W.G.copper wire to a heavy build. The excellent properties obtained aresummarized in Table II.

Blended Composition:

    ______________________________________                                        Component             Grams                                                   ______________________________________                                        Polymeric Amide-Imide-Ester (A)                                                                     687.0                                                   Polymeric Amide-Imide-Ester (B)                                                                     713.0                                                   Ester-Urethane-Isocyanate                                                                           335.0                                                   Phenolic Resin         76.5                                                   IPT (In 30 grams Cresylic Acid)                                                                      15.0                                                   ______________________________________                                    

AROMATIC POLYIMIDE AND AROMATIC POLYAMIDE-IMIDE OVERCOAT COMBINATIONSEXAMPLE 43

A #18 A.W.G. copper wire was coated with 2.6 mils of the compositiondescribed in Example 26 and overcoated with 0.4 mils of an aromaticpolyimide precursor solution which is the reaction product ofpyromellitic dyanhydride and 4,4'-diaminophenylether (availablecommercially from DuPont under the proprietary name ML). The markedimprovement in thermal life caused by the aromatic polyimide overcoat issummarized in Table II.

EXAMPLE 44

This example is identical to Example 43 except that the 2.6 milsundercoating was derived from the composition described in Example 11.Again, the effect of the aromatic polyimide overcoat on thermal life isnoted in Table II. An even better thermal life at 225° C. is obtained inthis example compared to that obtained in Example 43.

EXAMPLE 45

The blended composition of Example 37 was employed to provide a fourpass coating on #18 A.W.G. copper wire. A two pass overcoat of anaromatic polyamide-imide resin which was the reaction product oftrimellitic anhydride chloride and methylene dianiline (commerciallyavailable from American Oil Company under the proprietary name AI-537).The properties are summarized in Table II. It is apparent that therepeated abrasion resistance, heat shock resistance, baking range,flexibility, cut-through resistance and thermal life are excellent.

RESISTANCE TO HALOGENATED FLUOROCARBONS

Some applications of insulated electrical conductors require specialproperties in addition to those heretofore described. A hermeticallysealed motor-compressor is such an application because the insulatingcoatings of the windings are exposed to the halogenated hydrocarbonsthat are used as refrigerants. The insulating coatings must resistblistering when rapidly removed from the refrigerant and heated and mustretain abrasion resistance when immersed in the refrigerant. An exampleof a typical and widely used refrigerant is monochlorodifluoromethane(Freon 22). It should be understood, of course, that the insulatingcoating should retain, or sacrifice little of, the heretofore describedproperties.

The insulating coatings of this invention have a very high resistance tohalogenated hydrocarbons. Tests comparing the coatings of this inventionwith a widely used hermetic grade polyvinyl acetal resin indicate thesuperiority of the compositions of this invention. Soaking samples ofcoated wire in monochlorodifluoromethane for 24 hours at roomtemperature, cooling to -40° C., removing and rapidly heating thesamples to 150° C. caused the polyvinyl acetal samples to blister.Samples coated in accordance with Example 37 hereinabove showed noblistering.

Samples of coated wire were abraded with a 16 mil diameter knife edgeunder a 450 gram load while immersed in monochlorodifluoromethane. Thenumber of strokes to failure for the hermetic polyvinyl acetal wasinitially 850 and less than one with each of three samples that wereimmersed, respectively, 1, 4 and 7 days. Samples coated in accordancewith Example 37 hereinabove failed initially after 875 strokes and thenafter 550, 190 and 200 strokes, respectively, on samples immersed for 1,4 and 7 days.

NOVEL ESTER-URETHANE-ISOCYANATE COMPOUNDS

One of the components of some of the blended compositions describedhereinabove is an ester-urethane-isocyanate which is the reactionproduct of one mol of DMT, two mols of THEIC, and four mols of TDI.Details of the preparation are given in Example 27 hereinabove. Itshould be noted that a diester is first formed from the DMT and THEICand that the TDI is thereafter reacted with the diester. The reaction ofthe TDI is conducted in an excess of cresylic acid so that the reactiveisocyanate end groups of the product are blocked by forming an aromaticurethane. The blocking improves the tank stability of the product. TheNacconate 80 employed in Example 29 is an 80:20 by weight mixture of2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate.

Other polyisocyanates may be employed in place of the TDI to providecomponents suitable for use in insulating compositions. Dianisidinediisocyanate, 4,4'-diphenylether diisocyanate and 4,4'-diphenylmethanediisocyanate are examples of other suitable polyisocyanates.

Other lower dialkyl esters of terephthalic acid may be used in place ofthe DMT to form the diester with THEIC. isophthalic acid and lower alkylesters thereof may also be used as a substitute for DMT, in whole or inpart, but with less of an improvement in heat shock resulting insubsequent blends. Other phenols or mixtures thereof may be substitutedfor the cresylic acid.

While the utility of the ester-urethane-isocyanate has been heretoforeillustrated in blends containing the polymeric amide-imide-ester of thisinvention, it should be understood that this isocyanate may be blendedand/or reacted with polyester, polyester-amide and other similar wireenameling compositions. Indeed, this new polyisocyanate may be used incompositions and blends where the heretofore known polyisocyanates havebeen employed. The advantages of improved heat shock, solvent resistanceand coating range are obtained with this new polyisocyanate without theusual decrease in flexibility that is encountered with the addition ofother polyisocyanates.

Referring now to FIG. 1, conductor 10 while described in the foregoingexamples as a copper wire, may be of a metal such as aluminum, silver,either alone or as a plated or clad combination. After being cured inthe enameling tower or other heating means, the coating 11 adherestenaciously to the conductor 10. While the conductor 10 is illustratedas being circular in cross section, it may be of any other desirablecross-section such as square or rectangular. The conductor 10 may be aflat strip or a thin foil.

The compositions of this invention may also be applied to electricalconductors such as wire in combination with insulation, both organic andinorganic materials in film and/or fibrous form. One form of such acombination is illustrated in FIG. 2. A copper wire 20 is provided witha fibrous coating 21 impregnated with a solidified polymericamide-imide-ester resinous composition heretofore described. The fibrouscoating, which may be glass fibers, asbestos fibers, paper, cotton, silkor the like, may be either wrapped or braided about the conductor. Thecoating 21 may also be an inorganic film such as the aluminum oxideobtained by anodizing aluminum conductors in which case the resinousfilm would be bonded to the anodic films.

The resinous coatings of this invention may be applied to conductors incombination with and either under or over coatings of other resinouscompositions. FIG. 3 of the drawing is an illustration of theparticularly advantageous combination of coatings described specificallyin the foregoing examples. The metal conductor 30 is first coated with apolymeric amide-imide-ester film 31 and an overcoating 32 of an aromaticpolyimide (such as is available commercially from E. I. duPont as MLwire enamel) or an aromatic polyamide-imide (such as is availablecommercially from American Oil Company as AI-537). The advantages ofthese combinations are set forth in Examples 43, 44 and 45.

I claim as my invention:
 1. A polymeric amide-imide-ester coatingcomposition of (1) trimellitic anhydride, (2) an aromatic carbocyclicprimary diamino compound and (3) a polyol containing at least 3 hydroxygroups, wherein the molar proportion of (1):(2) for the amide-imidelinkages is from 0.8:1 to 1.8:1, said composition being soluble incresol, cresylic acid and phenol.
 2. The composition of claim 1 whereinthe aromatic primary diamino compound (2) is selected from the groupconsisting of methylene dianiline and m-phenylenediamine and the polyol(3) is tris(2-hydroxyethyl)isocyanurate.
 3. A polymericamide-imide-ester coating composition of (A) 40 to 55 equivalent percentof an acidic component comprising (1) at least 10 equivalent percent oftrimellitic anhydride, (2) up to 31 equivalent percent of at least oneacidic compound selected from the group consisting of isophthalic acidand the lower dialkyl esters of isophthalic and terephthalic acid, (3)up to 10 equivalent percent of at least one acidic compound selectedfrom the group consisting of aliphatic dicarboxylic acids containingfrom 4 to 10 carbon atoms and esters and anhydrides thereof, (4) up to 8equivalent percent of a titanate ester and (5) up to 10 equivalentpercent of a polyisocyanate (B) 45 to 60 equivalent percent of anamino-polyol component of (1) at least 8 equivalent percent of anaromatic carbocyclic primary diamino compound, (2) up to 5 equivalentpercent of an amino compound selected from the group consisting ofaliphatic primay diamines, melamine and piperazine, (3) at least 15equivalent percent of a polyol having at least three hydroxyl groups and(4) up to 25 equivalent percent of an aliphatic diol, said compositionbeing soluble in cresol, cresylic acid and phenol.
 4. The composition ofclaim 1 wherein said polyol (3) is a mixture oftris(2-hydroxyethyl)isocyanurate and another polyol containing threehydroxy groups.
 5. A polymeric amide-imide-ester coating composition of(1) trimellitic anhydride, (2) an aromatic carbocyclic primary diaminocompound, (3) a polyol containing 3 hydroxy groups and (4) an aliphaticdiol, wherein the molar proportion of (1):(2) for the amide-imidelinkages is from 0.8:1 to 1.8:1, said composition being soluble incresol, cresylic acid and phenol.